On Labor Day, a gunman opened fire in a Chicago-area train car, resulting in the deaths of four passengers: police.

On Monday morning, four individuals were fatally shot on a train in the Chicago area, as per Illinois officials.

At approximately 5:30 a.m. on Monday, authorities were summoned to a train station in Forest Park, a village in Cook County, due to a shooting that took place on a Chicago Transit Authority (CTA) Blue Line train.

At the scene, three people were declared dead, and the fourth victim passed away at a hospital. Chris Chin, deputy chief of the Forest Park Police Department, informed reporters that no further details about the victims are available.

A suspect who fled the scene was later arrested by authorities after being found on a CTA Pink Line train, according to FOX 32 Chicago.

"An isolated incident occurred on this unfortunate day, and a weapon was recovered, according to Chin. There is no immediate threat."

An excessive number of emergency calls have been made regarding the Forest Park train station, as stated by Mayor Rory Hoskins.

"Hoskins stated that it is a tragic event that four people lost their lives during Labor Day weekend. He added that their police and fire departments are likely to receive the most calls at this location within their jurisdiction."

The CTA condemned the shooting as "heinous and egregious" and pledged to aid law enforcement in their investigation.

The organization condemned the violent act that took place on a public transit train, stating that it was unacceptable and should never have happened.

The incident is being investigated by authorities. No further details are available.

The Associated Press contributed to this report.